The design and analysis of a MEMS electrothermal actuator

This paper introduces a type of out-of-plane microelectrothermal actuator, which is based on the principle of bimetal film thermal expansion in the fuse. A polymer SU-8 material and nickel are used as the functional and structural materials of the actuator. Through heating the resistance wire using electricity, the actuator produces out-of-plane motion in the perpendicular axial direction of the device and the bias layer contact with the substrate, completing signal output. Using Coventorware software to establish the three-dimensional model, the geometric structure is optimized and the electrothermal capabilities are determined theoretically. From electrothermal ana- lysis, the actuator＇s displacement is 18 #m and the temperature rises from 300 to 440 K under a voltage of 5 V and the response time is 5 ms. The actuator＇s displacement is 20μm under a 100000 m/s2 acceleration in the accelerating field. In the coupled field, applying a 3 V voltage, the initial temperature is 300 K, while the acceleration is 50000 m/s2, the driving displacement of the actuator is 23μm, and temperature rises to 400 K. Finally, through checking the stress in different field sources, the maximum stress of the actuator is smaller than the allowable stress of nickel. The results show that the electrothermal actuator has high reliability.

Low-voltage soft robots based on carbon nanotube/polymer electrothermal composites

Nowadays,soft robots have become a research hot spot due to high degree of freedom,adaptability to the environment and safer interaction with humans.The carbon nanotube(CNT)/polydimethylsiloxane(PDMS)electrothermal composites have attracted wide attention in the field of flexible actuations due to large deformation at low voltages.Here,the preparation process of CNT/PDMS composites was designed and optimized,and electrothermal actuators(ETAs)were fabricated by cutting the CNT/PDMS composite films into a“U”shape and coating conductive adhesive.The deformation performance of the ETAs with different thicknesses at different voltages was studied.At a low voltage of about 7 V,the ETA has a deformation rate of up to 93%.Finally,two kinds of electrothermal soft robots(ETSRs)with four-legged and three-legged structures were fabricated,and their inchworm-like motion characteristics were studied.The ETSR2 has the best motion performance due to the moderate thickness and three-legged electrode structure.